Anaphylactic Shock Nursing Care Management and Study Guide

Anaphylactic shock moves in minutes and it kills. A patient reexposed to an allergen drops their pressure, swells the airway, and crashes. Recognize it on sight, get epinephrine in, protect the airway, and support circulation. There is no time to wait on labs.

What is Anaphylactic Shock?

Anaphylactic shock is a systemic type I hypersensitivity reaction that is often fatal. Anaphylaxis floods the body with chemicals that push the patient into shock.

Pathophysiology

Anaphylaxis happens after reexposure to an antigen the patient has already made specific IgE against. On reexposure, the allergen cross-links surface-bound allergen-specific IgE on mast cells or basophils, triggering degranulation plus new synthesis of mediators. Immunoglobulin E (IgE) binds the antigen, then antigen-bound IgE activates FcεRI receptors on mast cells and basophils, releasing inflammatory mediators such as histamine. Most signs and symptoms trace to histamine binding its receptors; H1 receptor binding drives pruritus, rhinorrhea, tachycardia, and bronchospasm. Prostaglandin D2 mediates bronchospasm and vascular dilatation. Leukotriene C4 is converted into LTD4 and LTE4, which mediate hypotension, bronchospasm, and mucous secretion and act as chemotactic signals for eosinophils and neutrophils.

Statistics and Incidences

Worldwide, 0.05% to 2% of the population is estimated to experience anaphylaxis at some point. It occurs most often in young people and females. Of those who reach a US hospital with anaphylaxis, about 0.3% die. One peer-reviewed study put the likely rate at nearly 1 in 50 Americans (1.6%). The same research found 13% of cases occur at hospitals or clinics, 6.4% at a relative's or friend's home, 6.1% in the workplace, 6.1% in a restaurant, and 2.6% at school.

Causes

A severe allergic reaction can tip into anaphylaxis. Common triggers:

• Food allergies. The top triggers in children: peanuts, tree nuts, fish, shellfish, and milk.
• Medication allergies. Antibiotics, aspirin and other OTC pain relievers, and IV contrast used in some imaging tests.
• Insect allergies. Stings from bees, yellow jackets, wasps, hornets, and fire ants.
• Latex allergy. Develops after many previous exposures to latex.

Clinical Manifestations

An anaphylactic reaction produces a feeling of impending doom or fright first, then skin reactions (hives, itching, flushed or pale skin). Airway constriction and a swollen tongue or throat cause wheezing and troubled breathing. Hypotension is a major sign of shock. The heart compensates with tachycardia, trying to perfuse every system. Dizziness can progress to fainting.

Prevention

Because anaphylactic shock occurs in patients already exposed to an antigen and sensitized to it, it can often be prevented.

• Avoid allergens. Teach the patient to avoid known allergens, whether food, drug, or insect bite.
• Desensitization. If the patient must receive a drug they are allergic to, prevent a severe reaction with careful desensitization using gradually increasing doses of the antigen or advance administration of steroids.
• Monitoring. Watch closely during diagnostic tests that use radiographic contrast media, such as excretory urography, cardiac catheterization, and angiography.

Complications

• Respiratory obstruction. Severe inflammation can close the trachea.
• Systemic vascular collapse. Sudden loss of blood flow to the brain and other organs.

Assessment and Diagnostic Findings

Anaphylaxis is a clinical diagnosis, so labs are usually unnecessary and rarely helpful.

• Histamine and tryptase. Seen shortly after an episode, plasma histamine, urinary histamine metabolites, or serum tryptase may help confirm.
• 5-hydroxyindoleacetic acid. If carcinoid syndrome is on the table, measure urinary 24-hour 5-hydroxyindoleacetic acid.
• Food allergy testing. If history and exam suggest a food association, percutaneous (puncture) food allergen-specific skin tests and/or in vitro specific IgE tests (RAST or ImmunoCAP IgE) can be done, knowing both false-positive and false-negative results occur.
• Medication allergy testing. If history suggests penicillin and reagents are available, do penicillin skin testing with appropriate positive and negative controls.
• Insect sting testing. If history suggests a sting, do allergen-specific skin testing to Hymenoptera venoms.

Medical Management

• Remove the antigen. Stopping the cause, such as discontinuing an antibiotic, can halt the progression of shock.
• Administer medications. Give drugs that restore vascular tone and support basic life functions.
• CPR. If cardiac and respiratory arrest are imminent or have occurred, perform cardiopulmonary resuscitation.
• Establish an airway. Endotracheal intubation or tracheostomy may be needed.
• IV therapy. Insert IV lines for fluids and medications.

Pharmacologic Therapy

• Epinephrine. Given for its vasoconstrictive effect. In emergencies, give an immediate injection of 1:1,000 aqueous solution, 0.1 to 0.5 ml, repeated every 5 to 20 minutes.
• Diphenhydramine. Diphenhydramine (Benadryl) reverses histamine effects and reduces capillary permeability.
• Albuterol. Albuterol (Proventil) reverses histamine-induced bronchospasm.

Nursing Management

Nursing Assessment

Communication drives the assessment. Assess every patient for allergies and previous reactions to antigens, and assess their understanding of past reactions and what they and the family have done to prevent further exposure. When new allergies are found, advise the patient to wear or carry identification naming the specific allergen or antigen.

Nursing Diagnosis

• Impaired gas exchange related to ventilation-perfusion imbalance.
• Altered tissue perfusion related to decreased blood flow from anaphylactic vascular disorders.
• Ineffective breathing pattern related to swelling of the nasal mucosa.
• Acute pain related to gastric irritation.
• Impaired skin integrity related to changes in circulation.

Nursing Care Planning and Goals

Goals for the patient with anaphylactic shock:

• Maintain an effective breathing pattern: relaxed breathing at normal rate and depth, no adventitious breath sounds.
• Demonstrate improved ventilation: no shortness of breath or respiratory distress.
• Display hemodynamic stability: strong peripheral pulses; HR 60 to 100 beats/min with regular rhythm; systolic BP within 20 mm Hg of baseline; urine output greater than 30 ml/hr; warm, dry skin; alert, responsive mentation.
• Verbalize understanding of the allergic reaction, its prevention, and management.
• Verbalize the need to carry emergency components, inform health care providers of allergies, wear a medical alert bracelet or necklace, and seek emergency care.

Nursing Interventions

• Monitor the airway. Assess for the sensation of a narrowing airway.
• Monitor oxygenation. Track oxygen saturation and arterial blood gas values.
• Focus breathing. Coach slow, deep breaths.
• Position. Sit the client upright to promote maximum chest expansion, the position of choice in respiratory distress.
• Activity. Encourage rest and limit activity to the client's tolerance.
• Hemodynamic parameters. Monitor central venous pressure (CVP), pulmonary artery diastolic pressure (PADP), pulmonary capillary wedge pressure, and cardiac output/cardiac index.
• Monitor urine output. The renal system compensates for low blood pressure by retaining water, so oliguria is a classic sign of inadequate renal perfusion.

Evaluation

Expected outcomes: the client maintained an effective breathing pattern, demonstrated improved ventilation, displayed hemodynamic stability, and verbalized understanding of the reaction and the need to carry emergency components, inform providers, wear medical alert identification, and seek emergency care.

Discharge and Home Care Guidelines

Teach the patient and family about emergency medications and the plan to follow if a crisis recurs, and help them identify factors that precipitate or worsen crises.

Documentation Guidelines

Document assessment findings including respiratory rate, breath sounds, and the frequency, amount, and appearance of secretions; presence of cyanosis; lab findings; mentation; conditions that may interfere with oxygen supply; pulses and BP above and below the affected area; the client's description of pain, pain inventory, expectations, and acceptable level; prior medication use; plan of care, specific interventions, and who is involved; teaching plan; the client's responses to treatment, teaching, and actions performed; attainment of or progress toward the desired outcome; modifications to the plan; and long-term needs.